Told in flashback by a professor in an interview with a newspaper reporter, this is the story of The Stooges as traveling salesmen trying their best to sell their "Miracle Reducing Machine," which essentially shakes and rattles off the pounds (as Curly's demonstrates). As luck would have it, the boys stumble on the home of Graves the inventor (Ted Lorch), who assumed the Stooges are the new caretakers. Graves is on his way to Washington, D.C. to test his new death ray machine, and leaves his eerie spooky mansion in the hands of the trio. Naturally, spies disguised in Halloween costumes show up once Graves departs. The Stooges are on edge the entire time, particularly because mysterious cream pies come flying out of thin air.
The harried reporter finally asks, pacing frantically, "I can't stand this any more, Professor! WHO was throwing those pies?"
"Oh, I threw the pies!" chortles the professor, who gets one in the face himself as the short fades out!

The remake of the 1931 short The Great Pie Mystery which also directed by director Del Lord.

During World War II, the Stooges made a few comedies that engaged in propaganda against the then-enemy Japanese, including Spook Louder, Booby Dupes and The Yoke's on Me.

The title Spook Louder is a pun combining the request "speak louder" with the "spooks" of the mansion.

When the cuckoo with an owl in it opens, the strings tied to the clock door and the owl can be seen.

This film contains a few dubbing errors of the wrong voices for some of the actors. It happens several times throughout the film. First, when Curly yells after accidentally shooting the Stooges hat off the first time, his yell was dubbed in by Moe's. Next, after the master spy (played by Stanley Blystone) gets hit with a pie, for some reason, the mysterious pie-thrower's laugh heard the first time is actually Curly's. Finally, when the balloon attached to the back of Curly's jacket explodes behind him, we hear Moe's yell instead. Apparently, it is the same yell heard earlier in the film when Moe sees the spy, dressed as a devil, through the window.

Several scenes from Spook Louder can be seen in the 1992 film Radio Flyer.